Constant velocity universal joints are couplings used in automobiles to allow a rotational speed to be transmitted from a driving to a driven shaft which are not angularly aligned. One type of constant velocity universal joint commonly used in today's automobiles is the tripod universal joint. Tripod-type universal joints are characterized by a housing disposed around an inner joint which has a plurality of arms projecting therefrom for traveling in the grooves of the housing. A common feature of tripod universal joints is their plunging or end motion character. Plunging tripod universal joints allow the interconnection shafts to change length during operation and are currently the most widely used inboard (transmission side) joint in front-wheel drive vehicles.
The various types of tripod universal joints utilized today are often characterized by the different methods available for connecting or attaching tripod arms to the inner joint member. One variety of tripod joint exists in the art wherein a "spider" is splined to a drive shaft, the spider being an annular ring having three arms integrally formed thereon. At the upper portion of each arm, a trunnion is rotatably supported for riding in the grooves of the housing.
For background purposes, another method of tripod joint arm connection is shown by way of example in U.S. Pat. No. 4,384,860 ("the '860 patent") issued to Schmid. The '860 patent shows a constant velocity joint having a female joint half with three axial grooves. As disclosed therein, a trunnion is placed in each groove for making rolling contact against the sides of the grooves. Each trunnion has a turnpin for turningly supporting the rollers in a male joint half. It is this variety of tripod joint to which the teachings according to the present invention may be applied.
During articulation and angular movement of a constant velocity joint of the type disclosed in the '860 patent, movement of the joint components may result in sliding friction, particularly on the turnpins with respect to the male joint half. Further, due to the rotational movement of the turnpin in the male joint half, a constant velocity joint of this variety may sometimes experience noise, vibration and harshness, as well as shuddering, during operation. However, the '860 patent does not resolve these issues.
Consequently, an improved constant velocity joint design is desired for tripod joints having a female joint half, better known in the art as an outer joint or outer race, and a male joint half, which is commonly referred to in the art as an inner joint. This type of joint has trunnions which are supported within the male joint half. Such an improved design should seek to correct or alleviate any noise, vibration and harshness in this type of joint, as well as lessen any shuddering experienced during operation. Further, such an improved design should also reduce any sliding friction which may result from the radial movement and rotational movement of the turnpin with respect to the male joint half during operation.